JP2006176309A - Paper carrying method of image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper carrying method of an image forming device for simplifying control, even when connecting a postprocessing system of a speed faster than a process speed V1, by preventing carrying abnormality by looseness of a recording medium or motor operation abnormality by a strut of the recording medium caused by a difference in the uplifting step number in a speed increase, by dispensing with simultaneous switching of a plurality of motors sandwiched even when sandwiched by rollers of a different carrying speed. <P>SOLUTION: A cooling path unit having a path of the longest size or more of the recording medium regulated by at least the device, is equipped between switching rollers to a delivery path and a return path from a fixing part by driving a return vertical path roller by a return horizontal path roller driving motor. An interval between carrier rollers in the path is arranged in the shortest size or less of the recording medium regulated by the device. These carrier rollers are driven by a single motor, and a driving condition of the return path and the delivery path is set in the same. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sheet conveying method of an image forming apparatus represented by a printer, a copying machine, and the like, and more particularly, to a sheet conveying method between a switching roller from a fixing unit to a discharge path and a return path.

  An example of a conventional image forming apparatus is a tandem color laser printer as shown in FIG. The tandem color laser printer charges the surfaces of the photoreceptors 1y, 1m, 1c, and 1k corresponding to the respective colors (y: yellow, m: magenta, c: cyan, k: black) with chargers 2y, 2m, 2c, and 2k. The surface of the charged photoreceptor is exposed with optical devices 3y, 3m, 3c, and 3k according to image data, and the exposed image area is coated with toner (not shown) with developing devices 4y, 4m, 4c, and 4k. To develop a visible image. The developed visible image is sequentially superimposed and transferred onto the intermediate transfer belt 6 by the transfer machines 5y, 5m, 5c, and 5k, and the image data after the superimposed transfer is transferred to a recording medium (not shown) at the position of the second transfer roller 7. Is done.

  The transferred recording medium is transported to the fixing unit by the transport belt 8, and then melted and fixed by the fixing roll 9a and the pressure roll 9b. The fixed recording medium passes through the paper cooling pass roller 10a and the paper cooling pass roller 10b, and is conveyed to the discharge roller 15 side in the case of the discharged paper by the path switching roller 13, and returns after single-sided printing at the time of duplex printing. Control is performed so as to convey to the vertical pass roller 17 side.

  Further, as shown in FIG. 4, in the conventional conveyance sequence, the second transfer roller 7 to the path switching roller 13 are conveyed at the process speed V1, and the return vertical path roller 17 and subsequent ones are conveyed at the return speed V2 (V2> V1). Also, the discharge roller is usually conveyed at the process speed V1, but it is generally driven at a speed higher than the process speed V1 depending on the connected post-processing apparatus.

  In this case, since the path switching roller 13 and the return vertical path roller 17 are sandwiched between both the process speed roller and the return speed roller, the length of each recording medium is determined based on the leading edge detection sensor of the recording medium. Accordingly, the time required for the trailing edge of the recording medium to pass through the sheet cooling pass roller 10b is calculated, and the pass switching roller 13 and the return vertical pass roller 17 are conveyed at the process speed V1 until the trailing edge of the recording medium passes. Thereafter, control is performed to increase the return speed V2, and when the trailing edge of the sheet passes the path switching roller 13, control is performed to reduce the speed of the path switching roller 13 to the process speed V1 (see, for example, Patent Document 1). ).

JP-A-5-162914

  In the image forming apparatus described above, it is necessary to increase the speed of the path switching roller 13 and the return vertical path roller 17 at the same time T1 in order to keep the recording medium conveyed satisfactorily. The vertical pass roller drive motor 18 has a different gear ratio of the motor shaft due to the difference in motor use conditions and the like, and therefore the amount of movement of the roller in one step is different. There arises a problem that the conveyance operation due to the slack or the motor operation abnormality due to the recording medium pulling occurs.

  In addition, when a post-processing device having a speed higher than the process speed V1 is connected, the sheet cooling pass roller 10b needs to be switched in addition to the path switching roller 13 and the discharge roller 15, so that the drive motor for the sheet cooling pass roller 10b is used. , And the control becomes complicated and the same problem is built in.

  The present invention relates to an image forming unit having a photoconductor, a charger for charging the surface of the photoconductor, an optical device for exposing the charged photoconductor surface according to image data, and a developing unit for developing the exposed image area. The visible image developed on the plurality of photosensitive members is sequentially transferred to an endless belt or a recording medium that travels so as to sequentially pass through the plurality of image forming units, and then the transferred recording medium is heated.・ Return vertical pass roller drive motor drives the return vertical pass roller in an image forming device that pressurizes and fixes, and the recording medium for double-sided printing is transported to the return path unit, and the printed recording medium is transported to the discharge path unit. Cooling path unit that has at least a path larger than the maximum size of the recording medium defined by the device between the rollers that switch from the fixing unit to the discharge path and return path Equipped and arranges the interval between the conveying rollers in the path to be less than the shortest size of the recording medium specified by the device, drives these conveying rollers with a single motor, and sets the driving conditions of the return path and the discharge path It is characterized by being the same.

  According to the present invention, the transport roller drive in the return path can be driven by one motor, and the transport roller drive in the cooling path is also driven by one motor, so the motor drive control can be simplified.

  In addition, by installing a one-way clutch to the transport roller that still restrains the recording medium when the leading edge of the recording medium is restrained by the return roller or the discharge roller among the transport rollers in the cooling path unit. Even if it is pinched by rollers with different transport speeds, it is not necessary to switch the speed of the multiple motors that are sandwiched, so a transport error due to slack in the recording medium that occurs due to the difference in the number of startup steps at the time of acceleration, Alternatively, it is possible to provide a device capable of preventing motor operation abnormality due to the recording medium being pulled.

  Embodiments of the present invention will be described below with reference to FIGS.

  FIG. 1 is a schematic diagram of a drive unit configuration of a tandem color laser printer according to an embodiment of the present invention. The tandem color laser printer charges the surfaces of the photoreceptors 1y, 1m, 1c, and 1k corresponding to each color (y: yellow, m: magenta, c: cyan, k: black) with chargers 2y, 2m, 2c, and 2k. The surface of the charged photoreceptor is exposed with optical devices 3y, 3m, 3c, and 3k according to image data, and the exposed image area is coated with toner (not shown) with developing devices 4y, 4m, 4c, and 4k. To develop a visible image.

  The developed visible image is sequentially superimposed and transferred onto the intermediate transfer belt 6 by the transfer machines 5y, 5m, 5c, and 5k, and the image data after the superimposed transfer is transferred to a recording medium (not shown) at the position of the second transfer roller 7. Has been.

  The transferred recording medium is transported to the fixing unit by the transport belt 8, and then melted and fixed by the fixing roll 9a and the pressure roll 9b. The fixed recording medium passes through the paper cooling unit 10 and is conveyed to the discharge roller 15 side when the paper is discharged by the path switching roller 13, and to the return horizontal pass roller 19 side after single-sided printing at the time of duplex printing. It is controlled to be transported.

  In addition, the paper cooling unit 10 expects a cooling effect on the recording medium in the unit, sets the path length in the unit to be equal to or larger than the maximum size of the recording medium specified by the apparatus, and sets the interval between the conveying rollers in the path by the apparatus. The cooling pass roller 10a, the cooling pass roller 10b, the cooling pass roller 10c1 with a one-way clutch, and the cooling pass roller 10d1 with a one-way clutch, which are arranged below the minimum size of the specified recording medium, are driven by a single motor.

  FIG. 2 shows a motor drive sequence according to the present invention. The cooling pass roller drive motor 11 conveys at the process speed V1, and when the leading edge detection sensor 12 detects the leading edge of the recording medium, the return horizontal path motor is set to the return speed V2 and the discharge roller. The drive motor can be fixed at the discharge speed V1 (or the conveyance speed of the post-processing apparatus), and simple control can be performed in which only the path switching roller drive motor 14 is switched according to the conveyance destination of the recording medium.

  The path switching roller 13 shown in the above embodiment is placed in the sheet cooling unit 10 and is driven by the cooling path roller drive motor 11, and the path switching roller 13 is provided with a one-way clutch, so that the leading edge detection sensor 12 and the path are detected. Since the switching roller drive motor can be deleted and there is no motor for speed switching, the control can be further simplified and the cost can be reduced.

  The present invention can be used for an apparatus that has a conveyance path with a plurality of conveyance speeds and in which a conveyance member is sandwiched between conveyance rollers having different conveyance speeds.

It is a drive part structure schematic of this invention. It is a motor drive sequence of this invention. It is a drive part block diagram in a prior art. It is a motor drive sequence in a prior art.

Explanation of symbols

1y, 1m, 1c, 1k Photoconductor 2y, 2m, 2c, 2k Charger 3y, 3m, 3c, 3k Optical device 4y, 4m, 4c, 4k Developer 5y, 5m, 5c, 5k Transfer device 6 Intermediate transfer belt 7 Second transfer roller 8 Conveying belt 9a Fixing roll 9b Pressing roll 10 Cooling pass unit 10a, 10b, 10c, 10d Cooling pass roller 10c1, 10d1 Cooling pass roller with one-way clutch 11, 11a, 11b Cooling pass roller drive motor 12 Lead detection sensor 13 Pass switching Roller 14 Pass switching roller drive motor 15 Discharge roller 16 Discharge roller drive motor 17 Return vertical pass roller 18 Return vertical pass roller drive motor 19 Return horizontal pass roller 20 Return horizontal pass roller drive motor

Claims (2)

  There are a plurality of image forming units having a photoconductor, a charger for charging the surface of the photoconductor, an optical device for exposing the charged surface of the photoconductor according to image data, and a developing unit for developing the exposed image area. The visible images developed on the plurality of photosensitive members are sequentially transferred to an endless belt or a recording medium that travels so as to sequentially pass through the plurality of image forming units, and the transferred recording medium is then heated and pressure-fixed. In the image forming apparatus in which the recording medium for double-sided printing is conveyed to the return path section and the printed recording medium is conveyed to the discharge path section, the return vertical path roller is driven by the return horizontal path roller drive motor and discharged from the fixing section. Equipped with a cooling path unit that has at least the maximum recording medium size specified by the device between the path and return path switching rollers. The distance between the transport rollers is less than the minimum size of the recording medium specified by the device, and the transport rollers are driven by a single motor so that the return path and discharge path drive conditions are the same. A sheet conveying method of the image forming apparatus. Among the transport rollers in the cooling path unit, when the leading edge of the recording medium is restrained by the return roller or the discharge roller, a roller restraint release mechanism is provided for the transport roller that still restrains the recording medium. 2. A paper conveying method for an image forming apparatus according to claim 1, wherein

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